"Amazon is not too big to fail ... In fact, I predict one day Amazon will fail," Bezos reportedly said when addressing a question about Sears recently going bankrupt. "Amazon will go bankrupt. If you look at large companies, their lifespans tend to be 30-plus years, not a hundred-plus years."

While history shows that no empire lasts forever, it is unusual for CEOs — particularly a boss of one of the world's most successful companies — to talk down their firm in such unvarnished terms.

Bezos said that the goal was to delay the inevitable for as long as possible — and that the way to do that was to focus on customers.

"If we start to focus on ourselves, instead of focusing on our customers, that will be the beginning of the end ... We have to try and delay that day for as long as possible," he said.

Several Amazon employees who spoke with CNBC on the condition of anonymity said government regulation and potential antitrust violations were "big concerns" when looking to the future of the company.

"It's a fact that we're a large company," Bezos said in the recording heard by CNBC. "It's reasonable for large institutions of any kind, whether it be companies or governments, to be scrutinized."